The present invention pertains to the field of ophthalmology, and more particularly to a method and apparatus for marking contact lenses.
Contact lenses for the correction of vision are now in widespread use, providing a practical and sometimes advantageous alternative to glasses for most individuals requiring correction of imperfect vision. The first commercially successful contact lenses were the so called hard contacts, so named by virtue of their rigid construction. However, due in part to their rigidity, which made optimum fitting difficult to achieve, and in part to eye lubrication difficulties resulting from the relative impermability of the typical hard lens materials, acceptance of the hard contact lens was and still is limited.
In response to the drawbacks of hard contact lenses, flexible and permeable contact lenses were developed, and these types of contact lenses have come to be known as hydrophilic or soft contacts. The soft contact lens provides for a substantially better fit to the contours of the eye and additionally permits more natural eye lubrication by virtue of its permeable or hydrophilic properties. However, distinguishing between the left and right lens of a soft contact lens pair has proved to be considerably more difficult than in the case of hard contact lenses. Additionally, unlike the hard lens, the soft lens is subject to inversion and this too, like the above noted problem, is difficult to distinguish or identify until the lens is in place on the eye. In view of the relative difficulty of inserting and removing a lens, it is desirable that each lens is marked, usually near its edge, whereby identification of the right and left lens, as well as the proper orientation, i.e. inverted vs. noninverted, may be easily accomplished by the wearer before insertion.
Accordingly, lens marking methods and apparatus have been developed in the prior art. For example, British Patent No. 1,547,525, published June 20, 1979, discloses a chemical process and an apparatus for accomplishing the marking of lenses, for example, with the respective indicia "R" and "L". According to the apparatus disclosed, the lens to be marked is supported on a convex surface and a striker arm having a minute liquid absorptive relief area forming a marking indicia is provided. The absorptive relief area is soaked in an aqueous azo dye solution and then manually pressed against the contact in the appropriate location to transfer the solution to the lens in the manner of a printing process. The lens marking solution in the form of a marking indicia is thereby transferred to the lens and is thereafter made indelible by further chemical process.
While the above noted apparatus and its corresponding method can accomplish marking of contact lenses, it is relatively cumbersome, both with respect to the number of steps involved and with respect to the operation of mechanical apparatus. Consequently, the technique must be accomplished by relatively skilled technicians and is none the less vulnerable to human error. For example, the technician must maintain the relief area in an adequately soaked condition, apply an adquate but not damaging pressing force, and be sure to select the proper striking surface from several alternatives. Therefore, there is a need for a simpler and more foolproof lens marking apparatus and method, and such is provided by the present invention.